It is well known that electric motors and generators can be respectively used to convert electrical energy into mechanical energy and mechanical energy into electrical energy. Basically, both a motor and a generator operate on related physical principles. They both also involve similar operational structures, namely: a conductor, a magnetic field and an electrical current. On the one hand, for a motor (conversion of electrical to mechanical energy) a conductor is located in a magnetic field and an electrical current is passed through the conductor. Consequently, the magnetic field will exert a force on the conductor. This force can then be mechanically transferred from the conductor to do work (e.g. rotate a wheel on a vehicle). On the other hand, for a generator (conversion of mechanical energy into electrical energy) a conductor is physically moved in a magnetic field. The consequence of this movement is that an electrical current is set up or induced in the conductor. This induced current can then be stored (e.g. recharging a battery).
A Linear Synchronous Motor (LSM) is a particular type of electrical motor wherein the conductor (e.g. a three-phase winding) is laid out in a substantially linear configuration. The magnetic field is then moved along a path substantially parallel to the layout of the conductor (winding). The resultant force can then be applied to move a vehicle in a direction along the conductor (winding).
In its configuration, an LSM is noticeably different from the more conventional electric motors that have interactive magnetic fields and conductors. Typically, but not necessarily, the magnetic field in a conventional arrangement is held stationary while the conductor is rotated in the magnetic field. Despite their obvious configuration differences, in all other important aspects the basic physics of an LSM and a conventional electric motor are essentially the same.
For many applications, and for many different reasons, an electrical power plant (i.e. an electric motor) may be preferable to other types of motors (e.g. a fossil fuel combustion engine). In particular, more and more land vehicles are being equipped with electrical power plants. For example, many automobile manufacturers are providing battery-powered cars. LSMs are also being increasingly considered for use as the propulsion units of trains traveling over extended sections of railway lines. An important consideration for the use of an LSM as a propulsion unit for a vehicle, however, is that it effectively confines travel of the vehicle to the roadways where a stationary component of the LSM (e.g. the conductor/winding) has been pre-positioned. In some applications, however, it may be desirable to avoid such a limitation in favor of a more flexible travel envelope. If so, energy consumption requirements can become a concern.
In light of the above, it is an object of the present invention to provide a system that uses an LSM to propel an all-electric vehicle that may be alternately propelled by a battery-powered electric motor. Another object of the present invention is to provide an LSM vehicle propulsion system that initially synchronizes a waveform speed of the multiple-phase winding with the speed of the vehicle. Still another object of the present invention is to provide an all-electric vehicle propulsion system that is easy to use, relatively simple to manufacture and comparatively cost effective.